The Evolution of Cholera

Pathogenic strains of Vibrio cholerae are the causative agents of the diarrhoeal disease cholera, which continues to be a major health problem for human societies that lack sufficient safe drinking water and sanitation. Pathogenic strains isolated from different time periods and geographical loci are differentiated into various clones on the basis of several molecular characteristics. By looking at several aspects of evolutionary change, the results from this study clearly demonstrate that considerable evolutionary distinctions exist between the various pathogenic lineages of V. cholerae. Genetic mechanisms for evolutionary change; recombination, horizontal gene transfer, gene displacement and gene loss, have contributed to these genotypic distinctions and are likely to have been important in the divergence of the pathogenic clones from the common ancestral lineage. It would be expected that the same evolutionary processes are continually at work in creating shifts in the predominant pathogenic clone in endemic regions, and possibly lead to the emergence of the next pandemic clone of V. cholerae.